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• HS-SPME-GC-MS based simultaneous determination of multiple DBPs was developed. • The high-throughput method is reliable, free of organic solvent and time saving. • Sample preservation condition was investigated and suggested for actual samples. Disinfection by-products (DBPs) are detrimental to public health owing to their carcinogenicity and mutagenesis. Fast and reliable determination of DBPs is essential for ascertaining their formation, characteristics, and occurrence. This study reported an automated headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for quantifying typical nitrogenous-DBPs, including haloacetonitriles (HANs), trichloronitromethane, and trihalomethanes (THMs). The analysis was further optimized by selecting SPME fiber coatings, extraction/desorption time and temperature, and salt addition. The optimized method examined the occurrence and stability of the selected DBPs in aqueous samples under different preservation conditions and showed good sensitivity (limit of detection: 0.010–0.320 µg/L) and precision. Most THMs and HANs with high recovery were preserved in ultrapure water under dark and low-temperature conditions. However, real samples exhibited greater analytical biases due to comprehensive effects of photochemistry, biochemistry, and physiochemistry. Based on the findings of this study, we recommend that tested samples should be preserved in a frozen state and analyzed within three days. [ABSTRACT FROM AUTHOR]

Soil fumigation continues to play an important role in soil disinfection, but tools to significantly reduce emissions while providing environmental benefits (e.g., biochar) are lacking. The objective of this study was to determine the effects of biochar products on fumigant 1,3-dichloropropene (1,3-D) and chloropicrin (CP) emissions, their distribution and persistence in soil, nematode control, and potential toxicity to plants in a field trial. Treatments included three biochar products [two derived from almond shells (ASB) at either 550 or 900 °C pyrolysis temperature and one from coconut shells (CSB) at 550 °C] at 30 and 60 t ha−1, a surface covering with a low permeability film (TIF), and no surface covering (control). A mixture of 1,3-D (∼65%) and CP (∼35%) was injected to ∼60 cm soil depth at a combined rate of 640 kg ha−1. All biochar treatments significantly reduced emissions by 38–100% compared to the control. The ASB (900 °C) at both rates reduced emissions as effectively as the TIF (by 99–100%). Both fumigant emission reduction and residue in surface soil were positively correlated with biochar's adsorption capacity while cucumber germination rate and dry biomass were negatively correlated with residual fumigant concentrations in surface soil. This research demonstrated the potential and benefits of using biochar produced from local orchard feedstocks to control fumigant emissions. Additional research is needed to maximize the benefits of biochar on fumigant emission reductions without impacting plant growth. [Display omitted] • Biochar reduced 1,3-dichloropropene and chloropicrin emissions by 38–100%. • Biochar did not compromise efficacy of fumigants on Citrus nematode. • Almond shell biochar enhanced seed germination due to its nutrients. • Coconut shell biochar retained high fumigant residue and exhibited phytotoxicity. [ABSTRACT FROM AUTHOR]

Highlights: [•] The kinetics of dinoseb chlorination can be described by a second-order model. [•] Dinoseb chlorination is subject to hydroxylation, oxidation and substitution reactions. [•] High concentrations of TCNM and CF were generated and the yields varied with Cl2/C, time and pH. [•] TCNM formation favors acid pHs during dinoseb chlorination. [Copyright &y& Elsevier]

Content of the following compounds in water has been examined: trihalomethanes (trichloromethane, bromodichloromethane, dibromochloromethane, tribromomethane), haloacetonitriles (bromochloroacetonitrile, dibromoacetonitrile, dichloroacetonitrile, trichloroacetonitrile), haloketones (1,1-dichloro-2-propanone, 1,1,1-trichloro- 2-propanone), chloropicrin and chloral hydrate. In the period of 2011-2012 samples from terminal ends of the two water distribution systems in Krakow: 'Raba' and 'Bielany' were collected and analyzed. These systems differ in raw water quality, treatment train arrangement as well as distribution network size. Chlorination to disinfect the water is applied in both plants. The result analysis allowed assessment of seasonal variations (spring, summer, autumn, winter) in individual volatile chlorination by-product group content for each of the considered water distribution systems. Research conducted demonstrated significant infl uence of season-related water temperature fluctuations, therefore of the amount and type of precursors present in chlorinated water, on volatile halogen disinfection byproduct content formed in the water distribution system. [ABSTRACT FROM AUTHOR]

This study investigated the degradation kinetics, formation of disinfection by-products (DBPs), and degradation pathways during monochloramination of oxytetracycline (OTC). The degradation kinetics can be well described by a second-order kinetic model, first-order in monochloramine (NH2Cl), and first-order in OTC. Reaction of OTC with NH2Cl shows a high reactivity, with the apparent rate constant of 17.64/M/s at pH 7. The apparent rate constant declined as pH increased from 5 to 10. Six DBPs were detected during monochloramination of OTC, including chloroform (CF), 1,1-dichloro-2-propanone (1,1-DCP), 1,1,1-trichloro-2-propanone (1,1,1-TCP), dichloroacetonitrile (DCAN), trichloronitromethane (TCNM), and N-nitrosodimethlyamine (NDMA). CF, DCAN and NDMA had the maximum yields at neutral pH, while 1,1-DCP and 1,1,1-TCP had the maximum yields at pH 4. However, TCNM concentration increased as pH increased. Degradation pathways of OTC monochloramination were then proposed. Hydroxylation and Cl-substitution are found to be the dominant mechanisms in monochloramination of OTC. [ABSTRACT FROM AUTHOR]

Current best management practice programs in Florida aim to reduce water volumes needed for producing vegetable crops. Therefore, irrigation practices that save water while maintaining the economic sustainability of those crops are desirable. Field studies were conducted to determine the effects of water management regimes on tomato (Solanum lycopersicumL.) production and assess the effects of highly retentive mulches and methyl bromide alternatives on water volumes necessary for tomato irrigation. Twelve treatments resulted from combinations of fumigant, mulches, and irrigation programs. The combinations of fumigants and mulches were as follows: a) methyl bromide + chloropicrin (67:33 v/v) at a rate of 196 kg·ha−1under metalized mulch; b) 1,3-dichloropropene + chloropicrin (65:35 v/v) at 150 L·ha−1under metalized mulch; and c) 1,3-dichloropropene + chloropicrin (65:35 v/v) at 300 L·ha−1under high-density polyethylene mulch. Irrigation methods were seepage (subsurface) irrigation alone at 5000 and 10,000 m3/ha per season and the same seepage irrigation volumes combined with a drip irrigation volume of 3500 m3/ha per season. Increasing seepage volume from 5000 and 10,000 m3/ha in combination with drip irrigation did not increase average soil moisture, which ranged from 9.0% to 10.3%. Irrigation volumes affected soil moisture when only seepage irrigation was provided, with values increasing from 9.4% to 11.9% when water volumes increased from 5000 to 10,000 m3/ha, respectively. Only irrigation affected total marketable fruit weight. Adding drip irrigation to seepage-treated plots positively affected fruit weight, increasing yields from 36.5 Mg·ha−1in plots with only seepage to 39.5 Mg·ha−1. Increasing seepage irrigation from 5000 to 10,000 m3/ha in plots under drip irrigation improved yield from 34.5 to 44.5 Mg·ha−1. However, increasing seepage volumes in plots without drip irrigation did not affect tomato total marketable yields. [ABSTRACT FROM AUTHOR]

According to Article 12 of Regulation (EC) No 396/2005, the European Food Safety Authority (EFSA) has reviewed the Maximum Residue Levels (MRLs) currently established at European level for the pesticide active substance chloropicrin. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of chloropicrin are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses. [ABSTRACT FROM AUTHOR]

With methyl bromide's phase-out, most growers have turned to alternative fumigants, particularly 1,3-dichloropropene (1,3-D) and chloropicrin. These alternatives are tightly regulated because they are classified as toxic air contaminants and volatile organic compounds; the latter combine with other substances to produce ground-level ozone (smog). Two ambient air monitoring studies were conducted to evaluate the potential of totally impermeable film (TIF) to reduce emissions from shank applications of chloropicrin and 1,3-D. In 2009, a study demonstrated that TIF reduced chloropicrin and 1,3-D peak emissions by 45% and 38%, respectively, but TIF did not reduce total emissions when it was cut after 6 days. In 2011, increasing the tarp period from 5 to 10 days decreased chloropicrin and 1,3-D peak emissions by 88% and 78%, and their total emissions by 64% and 43%, respectively. Concurrent dynamic flux chamber results corroborated the ambient air monitoring data. These studies provide regulatory agencies with mitigation measures that should allow continued fumigant use at efficacious application rates. [ABSTRACT FROM AUTHOR]

The formation of total organic halogen (TOX), carbonaceous disinfection byproducts (DBPs) (trihalomethanes (THMs) and haloacetic acids (HAAs)), and nitrogenous DBPs (trichloronitromethane (TCNM) or chloropicrin, haloacetonitriles (HANs), and nitrosamines) was examined during the chlorination or chloramination of intracellular organic matter (IOM) extracted from Microcystis aeruginosa, Oscillatoria sp. (OSC), and Lyngbya sp. (LYN). The percentage of unknown TOX (22-38%) during chlorination indicated that the majority of DBPs were identified among THMs, HAAs, TCNM, and HANs. Bromide was readily incorporated into DBPs with speciation shifting slightly from dihalogenated species to trihalogenated species. During formation potential testing with chloramines, nitrosamine yields from IOM were measured for N-nitrosodimethylamine (NDMA, 10-52 ng/mgC), N-nitrosopyrrolidine (NPYR, 14 ng/mgC), N-nitrosopiperidine (NPIP, 3.7-5.5 ng/mgC), and N-nitrosomethylethylamine (NMEA, 2.1-2.6 ng/mgC). When IOM was added to a natural water matrix, the nitrosamine yields were not realized likely due to competition from natural organic matter. Ozonation increased NDMA and NMEA formation and reduced NPYR and NPIP formation during subsequent chloramination. In addition, ozone oxidation of IOM formed detectable concentrations of aldehydes, which may contribute to DBP formation. Finally, bioluminescence-based test results showed that >99% of the IOM extracted from OSC and LYN was biodegradable. Therefore, a biological treatment process could minimize this source of DBP precursor material during drinking water treatment. [ABSTRACT FROM AUTHOR]

Abstract: The non-regulated disinfection by-products (NrDBP) targeted in this study include four haloacetonitriles (trichloroacetonitrile (TCAN); dichloroacetonitrile (DCAN); bromochloroacetonitrile (BCAN) and dibromoacetonitrile (DBAN)); one halonitromethane (trichloronitromethane, better known under the name chloropicrin (CPK)); and two haloketones (1,1-dichloro-2-propanone (11DCPone) and 1,1,1-trichloro-2-propanone (111TCPone)). This study provides a detailed picture of the spatial and temporal variability of these NrDBP concentrations throughout a drinking water distribution system located in a region with major seasonal climate variations. The results obtained show that the concentrations of the investigated NrDBPs varied significantly according to time and location. The average concentrations of TCAN, DCAN, CKP and 111TCPone were significantly higher in summer. Surprisingly, the average concentrations of 11DCPone were significantly higher in winter. For BCAN and DBAN, the average concentrations observed in winter were higher, but not in a statistically significant way. On the other hand, the four HANs, CPK and 111TCPone generally had spatial profiles involving an increase of the concentrations along the network according to increasing water residence times, whereas 11DCPone overall had a profile where concentrations increased at the beginning of the network, followed by a drop in the concentrations towards the ends of the network. In spite of certain disparities in the individual spatio-temporal variation profiles, strong correlations were generally observed between NrDBPs, and trihalomethanes (THMs) and haloacetic acids (HAAs). Therefore, THMs and HAAs could be good statistical indicators of the presence of NrDBPs in the drinking water of the system under study. [Copyright &y& Elsevier]

Abstract: A gelatin capsule (gel cap) formulation of the mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) has been developed to reduce environmental emissions and potential human exposure from the use of 1,3-D/CP as a soil fumigant. The objective of the present study was to evaluate the biological efficacy of 1,3-D/CP gel cap formulations under greenhouse trial conditions. The current results indicate that a 1,3-D/CP gel cap formulation at 30 or 50 g a.i. m−2 can reduce the soil populations of Fusarium spp., Phytophthora spp., Pythium spp. and Meloidogyne spp.. In all tested crops, the 1,3-D/CP gel cap formulation provided marketable yields that were significantly higher than untreated controls and equal to the methyl bromide and 1,3-D/CP liquid injection treatments. Yields of tomato and a subsequent melon crop in plots treated with 1,3-D/CP gel cap were 93% and 87% greater, respectively, than the control. The yields of grafted cucumber and the subsequent balsam pear crop were increased by 16% and 201% respectively, compared to the control. The present study confirms that the tested 1,3-D/CP gel cap formulation provides a promising method for soil pest and disease control and reducing environmental emissions and potential human exposure in greenhouse vegetable cultivation. [Copyright &y& Elsevier]

Abstract: This study investigates the effects of water matrices with different natural organic matter (NOM) contents (3.00–6.50mg DOC/L) and different ozone doses (0.2 and 0.8mg O3/mg DOC) on changes in NOM structure and reactivity towards the formation of disinfection by-products. Water matrices differ in the NOM structure and other matrix characteristics (i.e. alkalinity, bromide content) which affect the NOM oxidation mechanism. Ozone treatment results in partial oxidation of the fulvic acid fraction, and increases the hydrophilic fraction (by up to 70%) with increasing ozone dose. A slightly lower degree of oxidability was found in the NOM dominated by the hydrophilic fraction and in water with the highest alkalinity. The residual hydrophilic fraction after ozonation was the most reactive towards trihalomethanes (THMs) and chloropicrin formation, with a higher proportion of brominated THMs in the hydrophilic non-acidic fraction. Bromate formation increases with increasing bromide content in the raw water and with increasing ozone dose, and achieves a significant level for drinking water quality at a dose of 0.8mg O3/mg DOC. [Copyright &y& Elsevier]

Abstract: Telone C-35, a commercial formulation of 1,3-dichloropropene (1,3-D) and chloropicrin (CP), is one of the potential replacements to methyl bromide (MB) for soil fumigation. A laboratory dose–response study and two field trials in tomato were conducted to evaluate their weed control efficacy and their effect on tomato yield. Laboratory studies found that the seeds of Digitaria chinensis were the most sensitive to soil fumigation with Telone C-35, followed by Eleusina indica, Portulaca oleracea and Stellaria media with the LC50 values between 3.35 and 11.68 mg kg−1 soil. Field trials revealed that Telone C-35 applied to the field at 327, 243 and 164 L ha−1 could suppress the percentage of germination weed seeds while maintaining high tomato marketable yields, with no significant differences between MB + CP and the higher two Telone C-35 rates. The yield data from both seasons indicated that all Telone C-35 treatments had a positive effect on tomato yield; there was a 32%–62% increase the mean marketable tomato yield. Our results indicated that Telone C-35 was an excellent MB alternative and could provide acceptable weed control efficacy. Based on our results, Telone C-35, in combination with other alternatives to MB, is recommended to achieve integrated pest management. [Copyright &y& Elsevier]

Abstract: Better quantification of nitrogen mineralization and nitrification after fumigation would indicate if any adjustment is needed in fertilizer application. The effects of chloropicrin (Pic), 1,3-dichloropropene (1,3-D), dimethyl disulfide (DMDS) and metham sodium (MS) fumigation on soil nitrogen dynamics were evaluated in lab incubation and field studies. Although some differences were observed in and concentrations in lab incubation and field experiments, both studies led to the same conclusions: (1) Soil fumigation was shown to increase soil mineral nitrogen only during the first 2weeks after fumigation (WAF). In particular, Pic significantly increased soil mineral nitrogen in both studies at 1 WAF. However, for all fumigant treatments the observed effect was temporary; the soil mineral content of treated samples recovered to the general level observed in the untreated control. (2) All the fumigation treatments depressed nitrification temporarily, although the treatments exhibited significant differences in the duration of nitrification inhibition. In both studies, for a limited period of time, Pic showed a stronger inhibitory effect on nitrification compared to other fumigant treatments. An S-shaped function was fitted to the concentrations of in lab incubation samples. The times of maximum nitrification (tmax ) in DMDS and MS treatments were 0.97week and 1.03week, which is similar to the untreated control (tmax =1.02week). While Pic has the longest effect on nitrifying bacteria, nitrification appears to restart at a later time (tmax =14.37week). [Copyright &y& Elsevier]

Abstract: Water application is a low-cost strategy to control emissions of soil fumigant to meet the requirements of the stringent environmental regulations and it is applicable for a wide range of commodity groups. Although it is known that an increase in soil moisture reduces emissions, the range of soil moisture for minimizing emissions without risking pest control, is not well defined for various types of soils. With two column studies, we determined the effect of different soil moisture levels on emission and distribution of 1,3-dichloropropene and chloropicrin in three different textured soils. Results on sandy loam and loam soils showed that by increasing soil moisture from 30% to 100% of field capacity (FC), peak fluxes were lowered by 77–88% and their occurrences were delayed 5–15h, and cumulative emissions were reduced 24–49%. For the sandy soil, neither peak fluxes nor the cumulative emissions were significantly different when soil moisture increased from 30% to 100% FC. Compared to the drier soils, the wetter soils retained consistently higher fumigant concentrations in the gas-phase, suggesting efficacy may not be impacted in these soils. The air-filled porosity positively and linearly correlated with the cumulative emission loss across all soil types indicating that it may serve as a good indicator for estimating emissions. These laboratory findings can be further tested under field conditions to conclude what irrigation regime should be used for increasing soil water content before fumigant application that can achieve maximum emission reduction and uniform fumigant distribution with high exposure index values. [Copyright &y& Elsevier]

Macrophomina phaseolina has been associated with serious crown rot losses in Australian strawberries in recent years. The fungus produces microsclerotia on standard media and dark ostiolate pycnidia when grown on sterile strawberry crown tissue and wooden toothpicks. Experiments in a glasshouse to confirm Koch's postulates indicated the pathogenicity of the fungus in two cultivars, Sugarbaby and Treasure. In the field, a range of soil fumigants killed buried microsclerotia, but only a mixture of methyl bromide and chloropicrin (50:50) eradicated the fungus in infected crowns buried in the soil. This work and worldwide reports suggest that this pathogen may become more important in strawberries in the absence of methyl bromide. [ABSTRACT FROM AUTHOR]

An automated headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method was developed to monitor the occurrence of selected haloacetonitriles (HANs), haloketones (HKs), and chloropicrin (CP) in drinking water supplies. The method was rapid with analysis time of 30 min, including extraction and chromatographic run. Chemical ionization (CI) was used to increase the sensitivity of the method for the HKs. SPME fibers with seven different coatings including commercial polyacrylate (PA), carbowax/divinylbenzene (CW/DVB), polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/ polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and a novel custom-made polydimethylsiloxane/divinylbenzene-N-vinylpyrrolidone (PDMS/DVB-NVP) were evaluated. The DVB/CAR/PDMS fiber was found more suitable for the range of the analytes and the novel PDMS/DVB-NVP fiber more efficient for the brominated acetonitriles under the experimental conditions. Method detection limits (MDLs) for the chlorinated acetonitriles and CP varied between 2 and 40 ng/L and for the brominated acetonitriles and HKs between 100 and 180 ng/L. Relative standard deviations (RSD %) of measurements were 4-7%. The method was applied in parallel with a liquid--liquid extraction gas chromatography electron capture detection (LLE-GC-ECD) method (EPA Method 551.1) to the analysis of drinking water samples from eight Canadian water treatment and distribution systems. The results generated by the two methods showed good agreement. [ABSTRACT FROM AUTHOR]

Abstract: Ozone (O3) and ozone/hydrogen peroxide (O3/H2O2) can be used in water treatment facilities to remove many organic micropollutants with taste, odor, and color implications. The effects of O3 and O3/H2O2 on the formation of disinfection byproducts (DBPs) in subsequent chlorination and chloramination processes, however, are not well determined. In this study, we compared the yields of a series of regulated and emerging DBPs during sequenced O3–Cl2, O3/H2O2–Cl2, O3–NH2Cl, and O3/H2O2–NH2Cl oxidation of 11 samples, each with different hydrophobicity, bromide concentration, soluble microbial products, and humic substances. For most water, pretreatment with O3 and O3/H2O2 increased the formation of chloral hydrate (CH), trichloronitromethane (TCNM) and haloketones (HKs) but lowered the yields of haloacetonitriles (HANs) during chlorination processes. Compared with O3 alone, O3/H2O2 in combination generated more CH and HKs during chlorination, and their extents of formation appeared to depend on the O3 doses. In terms of chloramination, both O3 and O3/H2O2 reduced THM, HAA, and HAN formation significantly without increasing CH, TCNM, or HKs. These results suggest that O3 or O3/H2O2 pretreatments may provide some benefits for the chloramination process in controlling regulated and emerging DBPs in waters without high bromide content. [Copyright &y& Elsevier]

A survey of 16 US drinking water treatment plants was conducted regarding the occurrence, formation, and control of emerging disinfection by-products (DBPs), with a focus on drinking waters that were impacted by treated wastewater and/or algae. The formation and control trends of certain emerging carbonaceous (haloacetaldehyde) and nitrogenous (haloacetonitrile, halonitromethane, cyanogen halide, nitrosamine) DBPs were different from those of the regulated trihalomethanes (THMs). This was due to differences in the sources of precursors (e.g., humic substances versus proteinaceous materials) plus differences in the effect of disinfection processes on these DBPs. For example, ozone increased the formation potential (FP) of chloropicrin (median = 226%), whereas biofiltration typically decreased the FP of the ozonated water (median = 48%), which--together with coagulation or softening--resulted (in general) in a net decrease (median = 33%) in FP through the ozone plants. Alternatively, coagulation with the polymer polyDADMAC (a source of N-nitrosodimethylamine [NDMA] precursor) increased the FP of NDMA (43-82%), whereas ozonation often destroyed NDMAFP (median to maximum = 10-87%). This article discusses how utilities can minimize and balance the formation of THMs and haloacetic acids with that of certain emerging DBPs. [ABSTRACT FROM AUTHOR]

Abstract: The phasing out of methyl bromide as a fumigant has prompted a search for possible alternatives. Here, the relative efficacy of soil solarization and fumigation with chloropicrin and 1,3-dichloropropene (CP+1,3-D) was evaluated in greenhouse-grown tomatoes. Experiments were conducted over two seasons in southern Italy, aimed at evaluating the effects of soil treatment on soil-borne pest control, and the vegetative growth and fruit production of tomato. Solarization provided a better level of control over the major fungal pathogens (Fusarium oxysporum f. sp. lycopersici and f. sp. radicis lycopersici, as well as Pyrenochaeta lycopersici) than CP+1,3-D fumigation. Solarization was also more effective in reducing the population of Meloidogyne spp. in the soil, and was particularly valuable for the suppression of the parasitic plant branched broomrape Phelipanche ramosa (syn. Orobanche ramosa). In both seasons, solarization was more beneficial than CP+1,3-D fumigation in terms of plant growth and crop productivity. In conclusion, solarization provided a good level of control over some important tomato pests and weeds, while at the same time improving the productivity in an environmentally friendly manner. It should therefore represent a viable alternative to methyl bromide fumigation for the greenhouse production of tomato. [Copyright &y& Elsevier]

Abstract: Chloropicrin is an aliphatic volatile nitrate compound that is mainly used as a pesticide. It has several toxic effects in animals and can cause irritating and other health problems in exposed humans. Since the mode of chloropicrin action is poorly understood, the aim of this study was to investigate molecular responses underlying chloropicrin toxicity. We used human retinal pigment epithelial cells (ARPE-19) as a model cell type because the eyes are one of the main target organs affected by chloropicrin exposure. Transmission electron microscopy images revealed that exposure to a chloropicrin concentration that decreased cell viability by 50%, evoked the formation of numerous electron-lucent, non-autophagy vacuoles in the cytoplasm with dilatation of the endoplasmic reticulum (ER). Lower concentrations led to the appearance of more electron-dense vacuoles, which contained cytoplasmic material and were surrounded by a membrane resembling autophagy vacuoles. According to immunoblotting analyses chloropicrin increased the amount of the ER-stress related proteins, Bip (about 3-fold compared to the controls), IRE1α (2.5-fold) and Gadd 153/Chop (2.5-fold), evidence for accumulation of misfolded proteins in the ER. This property was further confirmed by the increase of reactive oxygen species (ROS) production (2–2.5-fold), induction of heme oxygenase-1 (about 6-fold), and increase in the level of the tumour suppressor protein p53 (2-fold). Thus, the cytotoxicity of chloropicrin in the retinal pigment epithelium is postulated to be associated with oxidative stress and perturbation of the ER functions, which are possibly among the mechanisms involved in oculotoxicity of chloropicrin. [Copyright &y& Elsevier]

Abstract: The formation of trichloronitromethane (TCNM) and dichloroacetonitrile (DCAN) was investigated during chlorination and chloramination of 31 organic nitrogen (org-N) compounds, including amino acids, amines, dipeptides, purines, pyrimidones and pyrroles. Tryptophan and alanine generated the greatest amount of TCNM during chlorination process and asparagine and tyrosine yielded the highest amount of TCNM during chloramination process. Tryptophan, tyrosine, asparagine, and alanine produced more DCAN than other org-N compounds regardless of chlorination or chloramination. TCNM and DCAN formation was higher by chlorination than by chloramination. NH2Cl:org-N molar ratios, reaction time, and pH affected N-DBPs formation in varying degrees. TCNM and DCAN yields were usually high during chloramination of tyrosine, asparagine, and methylpyrrole under the following reaction conditions: NH2Cl:org-N molar ratios greater than 10, reaction time for 1d, and at pH 7.2. NH2Cl as a major nitrogen origin in TCNM and DCAN was confirmed via labeled 15N-monochloramine during chloramination of tyrosine, asparagine and methylpyrrole. In contrast, the majority of nitrogen in TCNM originated from glycine, and that in DCAN originated from pyrrole. Based on the intermediates identified by gas chromatography/mass spectrometry (GC/MS), a pathway scheme was proposed for TCNM and DCAN formation. [Copyright &y& Elsevier]

Implicated as a stratospheric ozone-depleting compound, methyl bromide (MeBr) is being phased out despite being considered to be the most effective soil fumigant. Its alternatives, i.e., 1,3-dichloropropene (1,3-D, which includes cis and trans isomers), chloropicrin (CP), and methyl iodide (MeI), have been widely used. High emissions of MeI from fumigated soil likely put farm workers and other bystanders at risk of adverse health effects. In this study, two types of constructed reactive film were tested for their ability to mitigate emissions of 1,3-D, CP, and MeI using laboratory permeability cells. Before activation, these films act as a physical barrier to trap fumigants leaving soil. After activation of the reactive layer containing ammonium thiosulfate solution, the films also act as a sink for the fumigants. Over 97% of trans-1,3-D and 99% of the cis-1,3-D, CP and MeI were depleted when they passed into the reactive film. Half-lives (t1/2) of cis-, trans-1,3-D, CP and MeI under activated reactive film were 1.2, 1.4, 1.6, and 2.0 h respectively at 40 °C. [ABSTRACT FROM AUTHOR]

Chloramines in drinking water may form N-nitrosodimethylamine (NDMA). Various primary disinfectants can deactivate NDMA precursors prior to chloramination. However, they promote the formation of other byproducts. This study compared the reduction in NDMA formation due to chlorine, ozone, chlorine dioxide, and UV over oxidant exposures relevant to Giardia control coupled with postchloramination under conditions relevant to drinking water practice. Ten waters impacted by treated wastewater, poly(diallyldimethylammonium chloride) (polyDADMAC) polymer, or anion exchange resin were examined. Ozone reduced NDMA formation by 50% at exposures as low as 0.4 mg×min/L. A similar reduction in NDMA formation by chlorination required ∼60 mg×min/L exposure. However, for some waters, chlorination actually increased NDMA formation at lower exposures. Chlorine dioxide typically had limited efficacy regarding NDMA precursor destruction; moreover, it increased NDMA formation in some cases. UV decreased NDMA formation by ∼30% at fluences >500 mJ/cm², levels relevant to advanced oxidation. For the selected pretreatment oxidant exposures, concentrations of regulated trihalomethanes, haloacetic acids, bromate, and chlorite typically remained below current regulatory levels. Chloropicrin and trichloroacetaldehyde formation were increased by preozonation or medium pressure UV followed by postchloramination. Among preoxidants, ozone achieved the greatest reduction in NDMA formation at the lowest oxidant exposure associated with each disinfectant. Accordingly, preozonation may inhibit NDMA formation with minimal risk of promotion of other byproducts. Bromide >500 μg/L generally increased NDMA formation during chloramination. Higher temperatures increased NDMA precursor destruction by preoxidants but also increased NDMA formation during postchloramination. The net effect of these opposing trends on NDMA formation was water-specific. [ABSTRACT FROM AUTHOR]

Although disinfection by-products (DBPs) occur in complex mixtures, studies evaluating health risks have been focused in few chemicals. In the framework of an epidemiological study on cancer in 11 Spanish provinces, we describe the concentration of four trihalomethanes (THMs), nine haloacetic acids (HAA), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), four haloacetonitries, two haloketones, chloropicrin and chloral hydrate and estimate correlations. A total of 233 tap water samples were collected in 2010. Principal component analyses were conducted to reduce dimensionality of DBPs. Overall median (range) level of THMs and HAAs was 26.4 (0.8–98.1) and 26.4 (0.9–86.9)μg/l, respectively (N=217). MX analysed in a subset (N=36) showed a median (range) concentration of 16.7 (0.8–54.1)ng/l. Haloacetonitries, haloketones, chloropicrin and chloral hydrate were analysed in a subset (N=16), showing levels from unquantifiable (<1μg/l) to 5.5μg/l (dibromoacetonitrile). Spearman rank correlation coefficients between DBPs varied between species and across areas, being highest between dibromochloromethane and dibromochloroacetic acid (r s =0.87). Principal component analyses of 13 DBPs (4 THMs, 9 HAAs) led 3 components explaining more than 80% of variance. In conclusion, THMs and HAAs have limited value as predictors of other DBPs on a generalised basis. Principal component analysis provides a complementary tool to address the complex nature of the mixture. [Copyright &y& Elsevier]

The gas-phase photochemical generation of CF3NO2 from CF3I and NO2 was found to be equilibrium limited. The formation of CF3NO2 is favored at low pressure and high temperature, where the concentration of the reactive species ꔷNO2 is the greatest, and unfavored at high pressure and low temperature, where the concentration of N2O4 is greatest. The results from varying the stoichiometric ratio of reactants, pressure, temperature, and reaction time in an attempted scale-up of this reaction are consistent with the reaction being equilibrium limited. The best reaction conditions allowed the generation of only 1–3 g of CF3NO2 per batch reaction in an approximate 16-L vessel. As long as reaction conditions are chosen so that all of the starting CF3I is consumed, caustic scrubbing affords a significantly faster, less expensive, and more practical purification method than those previously published. [ABSTRACT FROM AUTHOR]

Soil fumigation to control pests and pathogens is an important part of current agricultural practice. A reduction in fumigant emissions is required to ensure worker safety and environment health. A field trial in Florida was conducted to investigate whether carbonating Telone C35™ ((Z)- and (E)-1,3-dichloropropene with 35 % chloropicrin) would improve the delivery of the fumigant to such an extent that the application rate could be decreased without sacrificing efficacy. All treatments were carried out in three replications in a complete block design. The use of carbon dioxide (CO2) to carbonate and pressurize Telone C35 provided quicker and deeper distribution initially compared to application by nitrogen gas (N2) pressurization. The deeper distribution of Telone C35 components found with CO2application may have lowered the initial concentration of Telone C35, but it did not appreciably alter the disappearance rate of the three chemicals, chloropicrin, (Z)- and (E)-1,3-dichloropropene. The faster vertical distribution within the bedded soil of the Telone C35 by CO2did enhance volatilization of the active ingredients into the atmosphere compared to volatilization of similar reduced rate applied by N2pressurization. However, the cumulative amount volatilized from the carbonated fumigant beds at 75 % application rate was lower than the cumulative amount emitted by full rate of Telone C35 using N2. The efficacy of the carbonated Telone C35 at a lower application rate was statistically equivalent to that of non-carbonated fumigant using N2pressurized injection at a higher application rate, based on weed enumeration and the root-knot nematode galling index. [ABSTRACT FROM AUTHOR]

Abstract: A sampling survey investigated the formation of nitrogenous disinfection by-products (N-DBPs) and carbonaceous DBPs (C-DBPs) from pre-chloramination, an increasingly common treatment strategy in China for regulated C-DBP control, followed by subsequent conventional water treatment processes, i.e., coagulation, sedimentation, and filtration. Dihalogenated N-DBPs typically peaked in the summer and early autumn with a relatively higher temperature, with the maximum levels of dichloroacetamide (DCAcAm), dichloroacetonitrile (DCAN), bromochloroacetonitrile, dibromoacetonitrile and dichloroacetone at 1.8, 6.3, 6.0, 2.6 and 1.8μgL−1 in the finished water, respectively. Also, the levels of all the dichlorinated N-DBPs were correlated with the ratio of dissolved organic nitrogen (DON) to dissolved organic carbon, implying autochthonous DON played an essential role in the formation of these DBPs. In contrast, the yields of trihalogenated DBPs [chloroform (CF), trichloronitromethane (TCNM) and trichloroacetone (TCAce)] appeared not to be significantly affected by seasons. CF and DCAN were the dominant species in trihalomethanes (THMs) and dihaloacetonitriles (DHANs), respectively. Bromine was more readily incorporated into DHANs to form brominated DBPs than THMs during pre-chloramination. Although pre-chloramination can ensure the finished water to meet with the current Chinese THM regulatory limits, the increased levels of TCNM and TCAce may be a new water quality concern. [Copyright &y& Elsevier]

The aim of this study was to investigate the dynamics of dissolved organic N in soils fumigated separately with chloropicrin (CP), 1,3-dichloropropene, and metam sodium (MS) for 7 days and then incubated at 25°C for 84 days. The dissolved organic N (DON) at 14 days after fumigation was mainly dissolved amino acids (DAA) which were then rapidly mineralized to ammonium. However, the DON pool at later incubation times was mainly high molecular weight organic N which was resistant to microbial decomposition. Three soil fumigants all increased the proportions of DON in total dissolved N and DAA in DON. Dissolved organic N became much more important mobile N source in CP- and MS-fumigated soils, and this may increase the risks of DON leaching in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

The article cites a research study that evaluates 1,3-dichloropropene and chloropicrin emissions by field observations, soil modeling, and air dispersion analysis. It is said that soil fumigants are volatile compounds applied to farms to make the soil suitable for agriculture. However, only a small proportion of the near semi-infinite parameter combinations of environmental and agronomic conditions are covered by field trials used for measuring fumigant loss from soil to the atmosphere. A soil physics model for fumigant emission predictions is used in one approach to supplement field observations.

The article cites a research study that evaluates emissions produced by the application of soil fumigant chloropicrin (CP) through shank injection. It is said that a fundamental step for developing management strategies to reduce atmospheric emissions is knowing the control mechanisms of fumigant movement in soil. Vertical soil fractures are often left by CP application by shank injection that would potentially cause preferential fumigant movement and more emissions. Cumulative emissions and soil air concentrations of CP were compared to evaluate this potential transport pathway.

BACKGROUND: Producers of several high-value crops in California have traditionally used preplant soil fumigation with methyl bromide/chloropicrin combinations. Although methyl bromide has been phased out since 2005, several crop industries, including cut flower producers, have continued methyl bromide use under Critical Use Exemptions, a provision of the Montreal Protocol. This research was conducted to evaluate newer, emerging methyl bromide alternative chemicals. RESULTS: Two field trials were conducted to test several emerging chemicals in combination with metam sodium as replacements for methyl bromide. Emerging chemicals included 2-bromoethanol, dimethyl disulfide, furfural, propylene oxide and sodium azide. Weed and pathogen populations were measured after chemical application, and seed viability was assessed from weed seed previously buried in the plots. In the first trial, the emerging chemicals did not improve pest control compared with metam sodium alone. However, in the second trial, several of these chemicals did improve the pest control performance of metam sodium. CONCLUSIONS: The emerging alternative chemicals have the potential to provide better control of soilborne pathogens and weeds when used with metam sodium than metam sodium alone. Registration of these materials could provide California growers with a broader choice of tools compared with the limited methyl bromide alternatives now available. Published 2011 by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Fusarium wilt, caused by race 4 of Fusarium oxysporum f. sp. vasinfectum, is a critically important disease problem in California cotton (Pima, Gossypium barbadense; Upland, G. hirsutum). Because few cultivars with resistance to race 4 are available, alternative management strategies for this disease are needed. Four soil treatments (50:50 methyl-bromide + chloropicrin as a positive control; 60:40 chloropicrin + 1,3-dichloropropene; 6 weeks of solarization; and metam-sodium) were evaluated for efficacy against race 4 in a naturally infested, heavy clay soil. Treatments were evaluated based on plant mortality, height, number of mainstem nodes, vascular discoloration ratings, and soil counts of F. oxysporum. Two cultivars each of Pima and Upland cotton varying in resistance to race 4 were used. Plant mortality was lowest in methyl-bromide + chloropicrin, solarization, and chloropicrin + 1,3-dichloropropene treatments, and highest in the nontreated and metam-sodium treatments. Although most plant mortality occurred within 5 weeks after planting, substantial mortality of the susceptible Pima cultivar DP 744 accumulated for up to 10 weeks. Seven to eight weeks after planting, plants in methyl-bromide + chloropicrin and chloropicrin + 1,3-dichloropropene treatments were taller and had more mainstem nodes than in other treatments. Vascular discoloration was reduced in methyl-bromide + chloropicrin and solarization treatments compared with the nontreated control, metam-sodium, and chloropicrin + 1,3-dichloropropene treatments. Soil counts of F. oxysporum were significantly reduced only in the methyl-bromide + chloropicrin, chloropicrin + 1,3-dichloropropene, and solarization treatments. Six weeks of solarization and 60:40 chloropicrin + 1,3-dichloropropene (295 liters a.i./ha) proved effective for reducing Fusarium wilt of cotton in heavy clay soil. [ABSTRACT FROM AUTHOR]

The article presents a study to determine the effect of application and soil factors of fumigants in soil under commercial application that incorporate good agricultural practices (GAPs) in the U.S. Objectives of the study include quantifying vapor and non-vapor soil concentrations of methyl isothiocyanate (MITC), chloropicrin (CP) and dimethyl disulfide (DMDS) under commercial application scenarios which represents raised bed, plastic mulched vegetable production systems. Results of the study demonstrate an improved soil retention of agricultural fumigants.

Honeydew from phloem-feeding insects and fruit fly insecticidal baits may serve as adult food resources for some insect species. In California (USA) olive orchards, the black scale [ Saissetia oleae (Olivier) (Hemiptera: Coccidae)] is a common honeydew producer, and spinosad-based fruit fly bait (GF-120) is used to control the olive fruit fly [ Bactrocera oleae (Rossi) (Diptera: Tephritidae)]. We investigated the effects of black scale honeydew and GF-120, as food resources, on adult foraging behaviour and survival of the olive fruit fly and two parasitoids in the olive agroecosystem: Scutellista caerulea (Fonscolombe) (Hymenoptera: Pteromalidae), a natural enemy of black scale, and Psyttalia humilis (Silvestri) (Hymenoptera: Braconidae), a parasitoid of the fruit fly. In food choice tests, female flies did not show a preference between GF-120 bait and honeydew, whereas male flies and the parasitoids we tested preferred honeydew. Adults of the three insect species readily fed on honeydew, but the natural enemies never ( P. humilis) or rarely ( S. caerulea) fed on GF-120 bait. Olfactometer tests further confirmed that the tested natural enemies were not attracted to GF-120 bait. The presence of honeydew significantly reduced fruit fly mortality when both honeydew and GF-120 were provided, compared with GF-120 given alone. A single meal of honeydew increased longevity in all insect species tested. The mean longevities of honeydew-fed insects were not significantly different from those feeding on clover honey. Our results suggest that the presence of honeydew would benefit the three insect species and may reduce the efficacy of GF-120 for fruit fly control because of preference of honeydew rather than fruit fly bait as a food resource. [ABSTRACT FROM AUTHOR]

Abstract: The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV254 by coagulation–DAF-filtration was superior to coagulation–IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV254 were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7μgL−1, respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3μgL−1. However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN. [Copyright &y& Elsevier]

The application of UV disinfection in water treatment is increasing due to both its effectiveness against protozoan pathogens, and the perception that its lack of chemical inputs would minimize disinfection byproduct formation. However: previous research has indicated that treatment of nitrate-containing drinking waters with polychromatic medium pressure (MP), but not monochromatic (254 nm) low pressure (LP), UV lamps followed by chlorination could promote chloropicrin formation. To better understand this phenomenon, conditions promoting the formation of the full suite of chlorinated halonitromethanes and haloacetonitriles were studied. MP UV/postchlorination of authentic filter effluent waters increased chloropicrin formation up to an order of magnitude above the 0.19 μg/L median level in the U.S. EPA's lnformation Collection Rule database, even at disinfection-level fluences (<300 mJ/cm2) and nitrate/nitrite concentrations (1.0 mg/L-N) relevant to drinking waters. Formation was up to 2.5 times higher for postchlorination than for postchloranmination. Experiments indicated that the nitrating agent, NO2, generated during nitrate photolysis, was primariIy responsible for halonitromethane promotion. LP UV treatment up to 1500 mJ/cm2 did not enhance halonitromethane formation. Although MP UV/postchloramination enhanced dichloroacetonitrile formation with Sigma-Aldrich humic acid, formation was not significant in field waters. Prechlorination/MP UV nearly doubled chloropicein-formation compared-to-MP UV/postchlorination, but effects on haloacetonitrile formation were not significant. [ABSTRACT FROM AUTHOR]

Abstract: The phase-out of methyl bromide for preplant soil fumigation has resulted in an increased reliance on combinations of 1,3-dichloropropene and chloropicrin in many annual and perennial cropping systems in California. However, these fumigants also can have negative environmental and human health consequences and considerable research has been conducted on methods to minimize emission of these products from the soil to the atmosphere. To ensure that pest control efficacy is not compromised by emission reduction techniques, this research was conducted to simultaneously evaluate the effects of several surface seal techniques on fumigant emissions and the efficacy of soil-borne pest control with a mixture of 1,3-dichloropropene+chloropicrin. Results indicated that the interaction between emission reduction techniques and pest control efficacy can be complicated. For example in the 2006 trial, some surviving nematodes were observed in plots with both high (manure plus high density polyethylene film) and intermediate (pre-irrigation) 1,3-D cumulative emissions which suggested that emission loses are not solely responsible for some pest control failures. Weed control tended to be better with plastic film treatments and worse with pre-fumigation soil moisture manipulations but was affected less than expected by intermittent water seals. Although pest control clearly was affected by surface seal techniques, especially in shallow soil layers, some differences in nematode and weed control could not be explained solely by surface seals. These results underline the complex interactions among soil moisture and other environmental factors, application techniques, and emission reducing surface seal treatments. As new techniques and technologies become available to reduce fumigant emissions, we recommend that research include pest control efficacy evaluations before any emerging techniques are required by regulators or implemented by growers. [ABSTRACT FROM AUTHOR]

Abstract: Atmospheric emission of methyl isothiocyanate (MITC), chloropicrin (CP), 1,3-dichloropropene (1,3-D), and dimethyl disulfide (DMDS) were measured in the field under fumigant application scenarios representative of raised bed–plastic-mulched crop production systems. For three fumigation sites located in Florida, cumulative emissions of 1,3-D, MITC and CP were less than 11%, 6% and 2%, respectively. For three fumigation sites in located in Georgia, cumulative emissions of MITC and CP were <13% and 12%, respectively while DMDS emissions varied from 37% to 95%. In the Florida sites, emission peak flux of CP occurred within the first 6 h after application. Peak emission of 1,3-D and MITC occurred between 100 and 144 h after application. In the Georgia sites where fumigated soil was covered by low density polyethylene (LDPE) plastic, emission peak flux of DMDS and MITC occurred between 12and 48 h after application. Key factors affecting atmospheric emissions were soil moisture, soil tilth and the resistance to fumigant diffusion of the plastic film used to cover soil following application. This study demonstrated reduced atmospheric emissions of agricultural fumigants under commercial production conditions when applied using good agricultural practices including soil water contents above field capacity, uniform soil tilth in the fumigation zone and the use of metalized or virtually impermeable films to further reduce fumigant emissions. The results of this study show a need for regional flux studies due to the various interactions of soil and climate with local agricultural land management practices. [ABSTRACT FROM AUTHOR]

Fumigants are used to control soilborne pests before planting high-value crops such as strawberry. The use of specialized tarps during fumigation can reduce fumigant emissions and mitigate the need for large buffer zone requirements mandated by regulators. Increased fumigant retention by use of barrier films during fumigant application may increase fumigant retention and allow use of lower fumigant rates to control soil pests than would be needed with permeable film. The objective of this study was to determine the minimum effective rates of the alternative fumigants, 1,3-dichloropropene (1,3-D) + chloropicrin (Pic), and Pic required under virtually impermeable film (VIF) and a high-density polyethylene (HDPE) tarp to provide weed control equivalent to methyl bromide:chloropicrin (67/33% v/v MBPic) standard soil fumigation at 392 kg⋅ha-1 under HDPE. A second objective was to determine fumigant rates under VIF and HDPE tarps needed to provide weed control and the economic costs of using VIF and reduced rates of the alternative fumigants. In 2002-2003 and 2003-2004 growing seasons, the fumigants 1,3-D + Pic and Pic were tested at 0, 56, 112, 224, 336, and 448 kg⋅ha-1 under HDPE and VIF tarps at Oxnard and Watsonville, CA. An untreated control and a MBPic standard at 392 kg⋅ha-1 were also included in the study. Weed control was assessed using weed propagule viability bioassays for four common weeds, time required for hand weeding, and weed fresh biomass. The fumigant rate that would be needed for a 90% reduction in viability (GR90) for all weeds was 21% to 84% less for 1,3-D + Pic under VIF compared with the HDPE tarp. For Pic, the GR90 values were 5% to 64% less under VIF compared with the HDPE tarp. Hand weeding times and weed biomass decreased with increasing fumigant rates. With the exception of Pic in 2002-201)3 at Oxnard, VIF reduced the rate required for weed control compared with the HDPE tarp for both fumigants and at both locations. Economic benefits of VIF relative to the HDPE tarp were not consistent and additional work is needed to quantify these relationships and the production conditions under which VIF will be beneficial. [ABSTRACT FROM AUTHOR]